At this point it would be helpful if you stop thinking about your marks and ranks and instead simply concentrate on your fundamentals.

Don't stress yourself in any way and if you find your thoughts deviating, then read chemistry. There is a ton of stuff to learn for chemistry that is impossible to cover completely. Focus your efforts on improving your accuracy and speed. If you want to learn new concepts which are still very unclear, then only focus on those topics that are actually important. Do not waste time on the lesser important topics even if you don't know anything about them. (Although it might help to learn the formulae in case there is an easy question)

Once in a while, give mock tests to assess yourself. Don't attempt papers with the intention of trying to predict your rank. Just try to get as many marks as possible. Try to find where you're lacking and try to gain clarity in those topics.

Print out a sheet of the syllabus for the exam and cross out the topics one by one after you read them/practice them. This is a great motivator and works well if you are not self confident. The best way, according to me, would be to make a list of some important topics that you know you are good at and practice those very hard. It will not only strengthen your confidence but also give you a clearer mind and increase your accuracy and speed.

Good Luck!

Hey Gowtham there’s no need to lose confidence invest daily 5 hours for jee preparation prepare a proper time table for same

Join coaching institutes for clearing up your concepts they guide and assist u well

its not mandatory though I did myself self preparation using YouTube videos and other study material

purchase exam mocks so you can give test timely and evaluate where you lack.

Arihant.Hc verma,Tandon,Manjeet Singh are well knows authors

use Tata magraw hill For physics and chemistry 

Wish you all the best

if you have more queries you can ping me personally 

thank you